Integrated 2D and Depth Sensor Array With Phase-Shifted Charge Sampling
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Solution Overview
Problem
Existing image acquisition devices struggle to capture both a 2D image and a depth image without misalignment and bulkiness, as separate sensors or integrated pixels with reduced depth dimensions lead to inefficiencies.
Innovation Solution
A device with 2D image pixels and depth photosites, each equipped with capacitors and photodiodes, uses phase-shifted charge sampling to determine depth information, minimizing thermal noise and parasitic light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If separate image sensors are used to capture 2D image and depth image, then both images can be captured simultaneously, but misalignment between pixels occurs and device bulk increases
Solution Approach 1:
The patent combines 2D image pixels and depth photosites into a single integrated sensor array. Each depth photosite is positioned at the same location as its corresponding 2D image pixel, ensuring identical optical paths and eliminating misalignment between 2D and depth images. This merging approach maintains simultaneous capture capability while achieving perfect pixel correspondence.
Solution Approach 2:
The integrated sensor array serves multiple functions: 2D image pixels capture standard visual information while depth photosites at the same locations capture depth information through time-of-flight measurement. This multi-functionality allows a single device to perform both 2D imaging and 3D depth mapping without requiring separate sensors, thereby avoiding bulkiness while maintaining alignment.
2Measurement precision
If depth pixels are integrated in a same array with 2D pixels, then alignment is improved, but depth pixel dimensions must be decreased which causes information loss
Solution Approach 1:
The patent utilizes the temporal dimension to resolve the spatial conflict. Depth photosites measure the time-of-flight of photons by detecting phase shifts in reflected amplitude-modulated light signals. This temporal measurement approach allows depth photosites to maintain sufficient dimensions for accurate depth detection while being integrated in the same array as 2D pixels, avoiding the need to reduce depth pixel dimensions at the expense of information quality.
3Measurement precision
If depth photosites use multiple transistors for charge sampling, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates unnecessary transistors from the depth photosite circuitry. By using a simplified charge sampling architecture that relies on the inherent capacitance of the photodiode and sense node, the design achieves accurate depth measurement with minimal transistors. This extraction of redundant components reduces device complexity while maintaining measurement precision through efficient use of remaining circuit elements.
Solution Approach 2:
The depth photosite circuitry is designed to utilize the intrinsic properties of the photodiode and sense node capacitance for charge storage and sampling. The system leverages the natural capacitive characteristics of these components to perform multiple sampling operations without requiring additional dedicated storage capacitors or complex switching networks, thereby reducing overall device complexity while maintaining measurement accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables accurate depth estimation with reduced thermal noise and parasitic light interference, improving alignment and reducing device bulk and cost.
Implementation Method 1
each depth photosite comprising a photodiode, capable of detecting a reflected light signal corresponding to the reflection on the scene of an incident amplitude-modulated light signal
Data Source
AI summary
A device of acquisition of a depth image and of a 2D image of a scene, including depth photosites and capacitors, each depth photosite including a photodiode capable of detecting a reflected light signal, and at least one sense node coupled to the photodiode by a single transistor. Each capacitor is connected between the sense nodes of two photosites or between two sense nodes of a same photosite. Depth photosites supply the first plate of each capacitor with at least one first sample of charges photogenerated during first time periods, and supplying the second plate of each capacitor with a second sample of charges photogenerated during second time periods. Depth photosites supply the first plate of each capacitor with at least one third sample of charges photogenerated during third time periods.